Bioactive amines formation in milk by Lactococcus in the presence or not of rennet and NaCl at 20 and 32 °C

The influences of temperature, rennet and NaCl on bioactive amines formation in milk by a commercial starter culture containing Lactococcus lactis ssp. cremoris and L. lactis ssp. lactis were investigated. Sterilized reconstituted dry milk was inoculated with 1% culture in the presence or not of rennet and NaCl and incubated at 20 and 32 degreesC/24 h. The milk had pH 6.69, acidity 17.58 degreesD and low levels of agmatine, spermidine, spermine, and cadaverine. There was a decrease of pH, increase in acidity and change in the levels of natural-to-milk amines. Biogenic amines-histamine, serotonin, 2-phenylethylamine and tryptamine-were also formed. Tyramine was only formed at 32 degreesC. Rennet favoured the formation of natural-to-milk amines and also of putrescine, tyramine, and tryptamine. NaCl decreased agmatine, spermidine, putrescine, histamine and tyramine levels. By decreasing incubation temperature and adding NaCl, it is possible to minimize bioactive amines formation. (C) 2002 Elsevier Science Ltd. All rights reserved.